I recently purchased a Canon 7D, as my previous 450D had become a severely limiting factor in my endeavors to wildlife and bird photography (particularly bird photography, which I LOVE, but for which I have a bare handful of keepers out a few thousand shots.) The AF system of the 450D had a single cross-type point and a total of nine, while the 7D has a much more advanced 19 point system, all of which are cross-type. I've taken the 7D out a few times since I first purchased it, and while I have definitely had better luck photographing wildlife, I am still having trouble photographing birds on the move.

I have read through the 7D manual, however I am still not exactly sure where to start on learning how to use an advanced AF system in the real world for moving subjects. I could really use some insight from photographers who regularly use advanced AF systems for tracking subjects and keeping them in focus. I would also like to know how to take multiple shots of a subject on the move and keep them in focus between shots. While I can often nail one shot in a motion sequence, I regularly seem to fail to get proceeding or trailing shots after the one keeper (and that keeper is often not the most interesting one of the bunch.) The 7D supports a variety of AF modes as well, including AF Expansion and Zone AF, where the camera can supposedly utilize extra points around the selected point in case the subject moves away from the selected points area of sensitivity, or the selected point lands on a low-contrast part of the subject and a neighboring point lands on an area of high contrast (so focus can always be achieved, even if the selected point isn't detecting anything to focus on.) I have also not had much luck using either of these modes, and I think its primarily because I simply don't know how.

From a lens standpoint, I have used the following lenses:

EF 100-400mm f/4.5-5.6 L

EF 100mm f/2.8 Macro

EF 50mm f/1.4

My most frequently used lens is the 100-400, usually at the 400 end, so aperture is only f/5.6. I am not sure if that might be a problem or not (as far as I understand, the 7D supports AF at f/5.6, although I am not sure how many points might be considered "high precision" at that aperture.)

2 Answers
2

There are several custom function options available to the 7D which can be configured to assist with tracking moving objects:

C.FnIII -1 AI Servo Tracking Sensitivity
You want this set to "Slow" - this will stop the AF system trying to refocus on anything that briefly passes between you and the subject you are tracking - handy with birds where branches etc might flash by as you track

C.FnIII -2 AI Servo 1st/2nd Image Priority
This should be set to 0 so that the camera will give priority to focusing on the subject over taking shots - basically, if it thinks it hasn't got a lock, it won't shoot while it obtains one

C.FnIII -3 AI Servo AF Tracking Method
Set this to 1 - this further adds to the system ignoring obstacles by allowing the system to use AF points around the main focus point when something gets in the way of what you were tracking

Use single point AF with the AF Expansion custom function (C.FnIII -6) switched on - this gives you accuracy on the initial pick up but then allows the camera to help out as you track.

These settings should be correct from the camera side of things but the story doesn't end here.

Your 100-400mm L lens has a 2 mode IS system, with more predictable objects, you should use mode 2.

For tracking moving subjects it is important to get a good solid stance and to track the subject as it approaches some time before you want to start shooting (trickier with birds but achievable depending on the behaviour of the species). You should also follow through after you shoot (much like when shooting a shotgun).

You need your feet about shoulder width apart and need to be facing across the path of travel of the object you're tracking:

Object -------------------------------------------->

^
You

Hold the camera with your right hand as normal and with your hand a good way down the lens (similar to holding a rifle or shotgun). Keep your elbows tucked in, possibly resting against your torso to provide extra support and twist your torso from the hips upwards to meet what you want to track. Track it in the viewfinder, ideally if you can switch eyes so if you're tracking right to left, look through the viewfinder with your left eye so you can keep your right eye open to help keep track of the object (especially if it moves erratically) - do the opposite for left to right.

Start tracking the object, and smoothly pan with it. If you are shooting birds, turning off IS altogether is probably a good idea as the movement is likely to be too erratic for the IS to keep up with (even in panning mode 2) - aircraft are steady enough to use IS mode 2 with usually.

Squeeze the shutter release, don't press it (just like with a rifle) or it will jolt the camera and try to keep the object in the viewfinder as you get glances between shutter releases. Carry on tracking as the object moves away.

Getting a smooth torso twist is paramount and takes practice but getting the stance right gives you the foundations to build upon.

Thanks for the excellent tips! I'll experiment with those custom functions for servo mode. I haven't used servo mode much, and I've shot much more with one shot mode. Is servo mode required for the tracking to work? Are there any tips to using servo more properly?
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jrista♦Jan 21 '12 at 20:31

Yes, you need AI Servo for tracking, you won't have much joy with one shot. Those are pretty much my tips for its usage above
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JamWheelJan 21 '12 at 21:58

I understand. I read a few things that said the 7D focused between each shot, and I guess I figured that was with any AF mode. I'll start practicing with AI Servo mode more. One of the things I've noticed with servo mode, and what kept me off it, was that it wouldn't always nail focus...sometimes it would activate AF and stop, very close to but not actually focused, and take the shot. I'm wondering if thats because of C.FnIII-2, I may have set it to take the shot when I pressed the shutter button, rather than when focus was guaranteed.
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jrista♦Jan 21 '12 at 23:16

You need to keep the shutter half pressed for it to continue focusing and then squeeze it to take shots when you want, releasing it to a half press for continued focusing afterwards
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JamWheelJan 22 '12 at 8:57

So, if you are taking a continuous sequence of shots of a subject moving diagonally towards or away from the camera, and are just holding the shutter button down...does that mean AI Servo will not maintain focus on the subject between each frame?
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jrista♦Jan 22 '12 at 17:42

I shoot small birds at a bird feeder with a 70-200mm f2.8 + 2x teleconverter on a 1.5x crop-sensor Nikon DSLR (effectively 600mm). If you're also shooting small birds, my experience may be helpful.

I keep the camera on a tripod, with the ballhead loose so I can swivel quickly and easily. Holding the camera for any length of time is difficult not just because it's heavy, but because of the magnification, too: the slightest movement is a big jump in the frame.

I watch the birds for a while. Where are they coming from? Where are they going? What's their behavior as they come to the feeder? Trends become obvious and I can predict where they will likely land. Point the camera there.

Now, here's the surprising part: I often manually focus. I use a Nikon D300 with a 51-point AF system capable of dynamic area focus tracking that can lock focus very fast and is, in fact, the exact same AF system used in Nikon's top-of-the-line cameras. It is almost completely useless for photographing birds. The birds move super-fast, the branches get in the way, and at that magnification I don't have the agility to move the camera fast enough to keep up with them. It just doesn't work.

So, I use manual focus. I know where the birds are likely to land so I prefocus there. I also use the manual exposure mode and take a test shot or two to verify exposure looks good. I wait for the bird to come into the frame then recompose and refocus slightly, and take the photo.

I don't know what my good:bad shot ratio is, but as far as getting technically good photos, it's got to be well over 75%, maybe as high as 90%. (Aesthetically good is another matter!)

Hmm, I'm curious if you've tried to tune the AF system on your Nikon to support bird photography? I had similar problems with tracking with the 7D when I first tried using it...the AF would jump focus too fast, landing on foreground objects when a bird would pass behind them. JamWheel's tip of changing servo tracking sensitivity to slow really did the trick...I'm able to track even fast moving and even slower moving birds as they fly around, even when they fly behind foreground branches and the like. Once its configured properly, AF Servo Tracking feels essential to me now, and works great.
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jrista♦Feb 15 '12 at 19:34

I would try tuning your D300 AF settings, see if there is an option to lower the tracking sensitivity or whatever its called on Nikons. If you have savable custom settings on your dial, you should be able to configure a setting specifically for bird photography, save it to one of the custom dial modes, and be ready to do for bird photography in a heartbeat.
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jrista♦Feb 15 '12 at 19:35

Yes, this can be configured on Nikons. It works, so long as the branch is big enough or far enough away or steady enough to differentiate. When the branch is an inch or two in front, however, it's just too close to work well, particularly if a strong wind comes along and starts waving the branch while the bird stays still, for example. Depending upon the location, AF (and my "birds" preset!) are hugely useful, but for some circumstances MF is just easier.
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Dan WolfgangFeb 15 '12 at 19:50